1. Field of the Invention
Embodiments of the present invention generally relate to a method and apparatus for removing tubulars from a wellbore. Particularly, the present invention relates to a method and apparatus for increasing the amount of lifting force applied to a wellbore tubular when removing the tubular from the ground. More particularly still, the present invention relates to a method and apparatus for distributing the lifting force between two separate load surfaces for an increased lifting force. More particularly still, the present invention relates to controlling and monitoring a lifting force between two separate load surfaces.
2. Description of the Related Art
In the operation of oil and gas wells, it is common to remove well tubulars from the wellbore. Often such tubulars are stuck in the wellbore and therefore removal from the wellbore is difficult. The types of tubulars removed are casing, drill pipe, liner, production tubing, coiled tubing, or any other type of tubular used in a wellbore. Tubulars are removed from the wellbore for a number of reasons, such as remediation or to pull out and abandon the well. Currently, tubular removal uses an elevator of a drilling rig, or a hydraulic jack placed on the rig floor, or on the wellhead surface. These systems connect to the tubular and attempt to lift the tubular and break it free from the stuck point. The tubular is then lifted out of the wellbore.
The use of an elevator to pull wellbore tubulars may be dangerous and limited under heavy load situations. The elevator pulls at the tubular with a cable and pulley system. If the gripping apparatus or cables fail while pulling, a sling shot effect is created. The movement of the gripping apparatus or cables after failure creates a great risk to workers and equipment on the drilling rig.
In order to minimize hazards presented by elevators, it is known to use hydraulic jacks to pull wellbore tubulars. The hydraulic jack systems rest either on the rig floor or on the surface of the wellbore. However, when lifting tubulars from the wellbore either on the rig floor or wellbore surface alone are often insufficient for supporting the load required to break the tubular out of the ground. To solve this problem in the past additional structural members have been welded to the drill rig floor in order to increase the loading capacity of the rig. Further, if the hydraulic jack is placed on the wellhead, the jack often extends above the rig floor. Therefore, the rig floor has to be modified to allow the jack to pass through the floor. These approach is costly and time consuming.
Further, existing hydraulic jacking systems include a plate attached to the jack which has a closed circular aperture which surrounds the tubular during removal. However, if the tubular to be gripped continues above the rig floor, such as the case with coiled tubing, it is necessary to first cut the tubular before the jack is placed over the tubular.
Therefore, there is a need for an apparatus and method of removing tubulars from a wellbore that increases the load capacity of the lifting system without the need to modify a structure. There is a further need to lift tubulars from a wellbore without the need to cut the tubular during the jacking process.